Method for Arranging a Separating Piston in a Cavity and a Device with Such a Separation Piston

ABSTRACT

A steering damper system and method of regulating the fluid pressure of such a system are provided. The system can comprise a piston rod, a cylinder, a passage, and a damper portion. The damper portion can comprise a damper cavity, an outer piston, an inner piston, and a biasing component. The damper cavity can be in fluid communication with the passage. The outer piston can be slidably disposed in the damper cavity and define a chamber and a duct that is in fluid communication with the chamber and the passage. The inner piston can be slidably disposed in the chamber of the outer piston. The biasing component can exert an axial biasing force against the inner piston for regulating the pressure of fluid disposed in the system passes intermediate the passage, the damper cavity, and the chamber of the outer piston.

The present invention relates, among other things, to a method forarranging a separating piston in a system cavity where a liquid mediumis sealed off and separated from a second medium, for example gas (air),by means of the separating piston.

The invention also relates to a device with a separating piston in asystem cavity, for example a steering damper cavity, where the pistonseals off and separates a liquid medium from a second medium, forexample gas (air).

When arranging the separating piston in the cavity, the separatingpiston is to be positioned in the cavity in a position where it cancarry out its function with regard to maintaining the pressure within apredetermined pressure range. The system and the device must be able tocompensate for changes in volume as a result of changes in temperature,leakage, etc, so that the system, the steering damper, etc, has the samedamping characteristics in spite of the said varying factors.

The setting of the initial position of the separating piston in thecavity is critical and has hitherto involved a complicated method inwhich a special tool is used and it has been necessary to empty thesystem of the liquid medium in order to carry out the setting, which, inthe case of the replacement or repair of a separating piston in anexisting system that is in use, means that the whole system must beemptied of liquid in order to carry out the replacement or repair.

The objects of the present invention are, among other things, to solvethis problem and make possible non-critical setting of the initialposition of the separating piston even though the system is providedwith liquid. The separating piston is given an initial position thattakes into account any variations in pressure between the upper andlower sides of the separating piston resulting from the said temperaturevariations, leakage, etc.

The principal characteristics of a method according to the inventionare, among other things, that the liquid medium is introduced or hasbeen introduced into the cavity, that a first part of a piston comprisedin the separating piston is lowered into the liquid medium in adirection towards the inner part of the cavity, and that a second partof a piston comprised in the separating piston is lowered into thecavity and is caused to interact with the first part of the piston bythe application of an interaction force, for example via an actuatingarea located on the second piston. A volume of liquid is therebyconfined between the parts of the piston by the said interaction and,following the said interaction, the second part of the piston issubjected to downward-pressing forces, for example via the saidactuating area, with the result that parts of the second piston areurged to continue to penetrate into the first part of the piston. As aresult of this, all or parts of the confined volume of liquid are forcedout into the cavity under the first part of the piston via a passage inthis, whereupon the volume of liquid thus forced out acts upon a lowerarea that is larger than the in the first piston part down-pressed areaof the second piston part. As a result of the difference in area betweenthe in the first piston part down-pressed area of the second piston partand the lower area, the downward-pressing force causes the first part ofthe piston to move upwards in relation to the second part of the piston.The motion is ended when the first and second piston part is pressedtogether into a final position, so that the separating piston as such isat a distance from the said inner parts of the cavity. A springfunction, for example a mechanical spring, is finally arranged to act onthe separating piston at the upper part of the second part of thepiston.

The principal characteristics of a device according to the inventionare, among other things, that the separating piston can comprise firstand second parts of the piston, that the first part of the piston isarranged to be able to be inserted into the liquid medium towards theinner parts of the cavity and that the second part of the piston issimilarly arranged to be able to be inserted into the liquid medium andis able to be partially pressed down, by downward-pressing forces, intothe first part of the piston. In the partially pressed-down position ofthe second piston, the first and second parts of the piston contain avolume of liquid medium and the first piston is provided with a passageleading in a direction towards the said inner parts, which passage isarranged to allow all or parts of the confined volume of liquid mediumto pass through as a result of the downward-pressing forces. The firstpiston has a lower area and the second piston has a down-ward pressedarea. The lower area is larger than the down-ward pressed area and thedownward-pressing forces cause the volume of liquid medium that has beenforced out to make contact with the lower area and hence cause the firstpart of the piston to move from the said inner parts towards the secondpart of the piston to a final combined position for the parts of thepiston at a distance from the inner parts. In order to maintain thedownward-pressing forces and pressurization of the liquid medium, thesecond piston can interact with a spring function.

In further developments of the concept of the invention, the first partof the piston is tubular and has an inner cavity that receives parts ofthe second part of the piston. An end part comprises the said passage inthe form of a central hole that extends through the first part of thepiston, and the first part of the piston can have a seal at the end partthat can interact with the inner wall of the system cavity. The end partcan have the lower area on its outside. The second part of the pistoncan be arranged to be able to be inserted in the inner cavity of thefirst part of the piston and can be sealed against the inner wall ofthis cavity by means of a sealing arrangement. In an additionalembodiment, the actuating area of the second piston can comprise anouter flange surface, upon which the spring function, in form of amechanical spring, can be arranged or can make contact. In addition, thesecond part of the piston can have a central part that extends upwards.In addition, the said distance is selected to ensure that the separatingpiston, comprising the first and second parts of the piston, carries outmovements within the system cavity within the limits in which theseparating piston is to operate. A considerable part or all of theconfined volume of liquid medium can have been forced out through thepassage when the downward-pressing forces cause the parts of the pistonto assume a completely combined or pressed-together position. At itsouter end surface, the first piston can have a peripheral contactsurface that can make contact with a corresponding stop surface in theinner part of the system cavity, and the inner part can have an openingthat is opposite the central hole in the first part of the piston, intowhich the confined volume of the liquid medium is initially able to beforced down.

By means of what is proposed above, a reliably-operating andadvantageously-constructed separating piston is obtained that, in spiteof the fact that it comprises two parts of a piston, can be constructedin such a way that the parts of the piston maintain their relativepositions in a combined position as a result of the ratio of theirareas. The system can be filled with liquid when the piston is insertedand the distance to the inner parts can be given a value that enablesthe separating piston to operate within fixed or predetermined limitvalues in, preferably, a steering damper.

Currently proposed embodiments of a method and a device will bedescribed below, with reference to the attached drawings, in which

FIG. 1 shows in vertical section a steering damper, and

FIGS. 2 a-2 b show in vertical section parts of an accumulator comprisedin the steering damper according to FIG. 1, in which the parts of the apiston assume different positions in relation to each other when themethod is implemented.

FIG. 1 shows a steering damper represented by 1, the basic constructionof which can be of a known type and, for example, consists of the ÖhlinsSD100 or SD200 steering damper sold on the general market by theapplicant of the present patent application. The steering dampercomprises mounting devices 2 for mounting the steering damper onto thehandlebars of a motorcycle, cycle, etc, (not shown in FIG. 1). Inaddition, there are mounting devices 3 for mounting it to the frame orchassis of the vehicle (not shown). The steering damper comprises apiston rod 4 extending in the longitudinal direction of the damper thathas mounting devices 3 at one end. A piston (piston arrangement) 5 isfixed on the piston rod, which piston operates in a liquid medium 6 thathas been introduced into the cavity 7 of the steering damper. Thecavity, the piston rod and the piston can be mounted on a part 8, in oron which the first mounting device is arranged. The piston rod ismounted so that it passes through the ends of the part 8 and has sealingdevices 10 that allow a movement between the rod and the part 8. Thesteering damper also has a unit 11 that is connected to the part 8,which unit 11 comprises a duct system with ducts 12, 13 and 14 that makepossible for liquid to pass between the upper and lower sides 5 a and 5b of the piston 5, in other words, that connect the partial cavity 7 aabove the piston with the partial cavity 7 b below the piston. In theembodiment, the unit 11 also comprises a reservoir for a unit 15 thatmaintains the pressure of the liquid and that ensures that the steeringdamper can retain its damping characteristics within predeterminedvariations in temperature, in the event of minor leakage in the steeringdamper, etc. In FIG. 1, the unit is also shown enlarged and in aprotruding position and has accordingly been given the reference numeral15′. The unit 11 has a longitudinal opening 16, in which the unit 15,15′ is mounted. The unit 11 is also provided with a pressure-regulatingdevice 17 of a known type. The unit 15, 15′ shows a piston arrangement18 that acts as a separating piston between the liquid (for examplehydraulic oil) 6 in the steering damper (the system) on the underside 18a of the separating piston and a gaseous medium 19, (for example air),on the upper side 18 b of the separating piston. The unit 15, 15′ has acavity 20, with the partial cavities 20 a and 20 b for the gas andliquid mediums. On the separating piston 18, there is a spring, thatconsists of a spiral spring 21 in the example illustrated, that is incontact with an actuating area 18 p. The spring is attached between theactuating area and an internal surface 22 on a part (a nut) 23 thatcloses the cavity 20 and the separating piston 18 operates against theeffect of the spring function, that can also be achieved by other meansand arrangements. At its other end, the unit 15, 15′ is provided with aconnecting arrangement 24 for connecting the partial cavity 20 b to theduct arrangement. At one end, the unit 15, 15′ has a sealing element 25that seals the unit against an inner surface on the cavity 16. Theseparating piston is provided with a sealing element 26 that seals offthe unit against an inner surface 20 c in the cavity 20. The cavity 20 ais connected to the surrounding atmosphere 27 via a passage (hole) 28,for example in the said nut 23 that is connected to the unit 15, 15′ insuch a way that it forms a seal. A (tubular) part, which surrounds thecavity 20 and the separating piston 18, is indicated by 29.

FIGS. 2 a and 2 b show the assembly and the arrangement for theconstruction of the piston 18 in greater detail. The method can beconsidered to work in three steps or phases, with FIG. 2 a showing thefirst step, FIG. 2 b showing the second step and FIG. 1 showing thethird step.

In step 1, the liquid medium 6 is introduced or has been introduced intothe cavity, whereupon a first part of a piston 18 c comprised in theseparating piston 18 is inserted down into the liquid medium in adirection towards the inner part 30 of the cavity. The first part of thepiston 18 c has a lower area 18 f on the underside 18 a of theseparating piston. In the second step, a second part of a piston 18 dcomprised in the separating piston is inserted down into the cavity 20and is caused to interact with the first part of the piston 18 c by theapplication of an interaction force F1 via an actuating area 18 e and/or18 p located on the second piston. A volume 31 of the said liquid 6 isthereby confined between the parts of the piston 18 c and 18 d by thesaid interaction. In the third step, the second part 18 d of the pistonis subjected to downward-pressing forces, via the said actuating area 18e and/or 18 p, that correspond to or exceed the said forces F1.

Application of this downward-pressing force results in an overcome ofthe friction forces between the first 18 c and the second 18 d pistonpart and parts 18 g of the second piston 18 d are urged to continue tobe inserted into the first part of the piston 18 c. As a result of this,all or parts of the confined volume of liquid 31 are forced out into thecavity 32 below the first part of the piston 18 c via a passage 33 inthis. The forced-out volume of liquid acts upon a lower area 18 f of thefirst piston part 18 c that is larger than the by the part 18 g in thefirst part 18 c down-ward pressed area 18 h. As a result of thedifference in area of the down-ward pressed area 18 h and the lower area18 f, the first part of the piston 18 c will be caused to move upwardsin relation to the second part of the piston 18 d by thedownward-pressing force F1 and, in a final position in which it ispressed together with the second piston, the separating piston as suchis at a distance A from the said inner parts of the cavity. The saidspring function 21 can thereafter be caused to act against theseparating piston at the upper part 18 e of the second part of thepiston or the actuating area 18 p that is also assumed to be located onthe upper part. The second part of the piston has a sealing arrangement34 for sealing the second part of the piston against an inner surface 35of the first part of the piston that has an inner cavity 36 for thesecond part of the piston. The second part of the piston also has aninternal guide 37 for the spring. The spring 21 extends down between theguide and an inner wall in the first part of the piston to interact withthe actuating area 18 p and in this way control is achieved.

Thus, when inserted into the liquid, the separating piston comprisesfirst and second parts of the piston 18 c and 18 d that can be pressedtogether. The ratio of the down-ward pressed area 18 h and the lowerarea 18 f is selected in such a way that the relative combined positionsestablished at the time of the insertion are retained when the springfunction 21 is applied. Before the second part 18 d of the piston isinserted into the first part 18 c of the piston, the lower area 18 a ofthe first 18 c piston part rests on a stop surface 38 of the inner part30. While it is being inserted, the piston is raised from the innerparts 30 of the cavity by the distance A that ensures pressurizationthat provides the same damping characteristics in the damperirrespective of variations in temperature, leakage, etc. The inner part30 can also include an opening/cavity 32 that is opposite the centralhole 33 in the first part of the piston 18 c, in which the confinedvolume 31 is initially able to be forced down. In an embodiment, thewhole confined volume 31 is initially forced out between the parts 18 c,18 d of the piston. By the expression “upper part of the second part ofthe piston” is meant the actual part of the piston without the guide 37.In an embodiment, the second part of the piston does not need to bepressed into the first part of the piston but is over the first part ofthe piston and hence confines a volume in a corresponding way.

The invention is not limited to the embodiments described above but canbe modified within the framework of the following claims and concept ofthe invention.

1-10. (canceled)
 11. A method for regulating pressure of a fluid in asteering damper system, the method comprising: filling a damper cavitywith the fluid; placing an outer piston into the damper cavity such thatthe outer piston is slidably disposed in the damper cavity and forms afluid-tight seal with an interior surface of the damper cavity, theouter piston defining a chamber and a duct, the duct being in fluidcommunication with the chamber and the fluid in the system; moving theouter piston downwardly into the damper cavity such that the outerpiston is submerged in the fluid, the fluid passing through the duct inthe outer piston and into the chamber of the outer piston; placing aninner piston into the chamber of the outer piston such that the innerpiston is slidably disposed in the chamber of the outer piston and formsa fluid-tight seal with an interior surface of the chamber; exerting anaxial force against the inner piston such that fluid disposed in thechamber of the outer piston is urged into the damper cavity through theduct of the outer piston and until a lower surface of the inner pistoncontacts a stop surface of the chamber of the outer piston; and biasingat least a portion of the inner piston against a portion of the dampercavity.
 12. The method of claim 11, wherein the outer and inner pistonsare positioned at a given distance above a bottom surface of the dampercavity after the lower surface of the inner piston contacts the stopsurface of the chamber of the outer piston.
 13. The method of claim 11,wherein the step of biasing at least a portion of the inner pistoncomprises inserting a spring into the damper cavity.
 14. The method ofclaim 13, further comprising biasing the spring against an internalsurface of a closure part being connected to the damper cavity forclosing the damper cavity.
 15. The method of claim 11, furthercomprising the step of adjusting an available volume of the system usinga pressure regulation device, the system comprising a passage being influid communication with the damper chamber, the pressure regulationdevice being operative to vary the volume of the passage.
 16. A steeringdamper system comprising: a piston rod comprising an elongate shaft, apiston component and a mounting section, the piston component beingfixed along the shaft of the piston rod and defining a diameter largerthan a diameter of the shaft; and a damper module comprising: a cylinderdefining top and bottom ends, the cylinder being configured with thepiston rod being slidably disposed therein, the cylinder defining aninner surface having a diameter greater than the diameter of the pistoncomponent to form a seal with the piston component, the cylinderdefining upper and lower sections, the upper section being that portionof the cylinder intermediate the piston component and the top end of thecylinder, the lower section being that portion of the cylinderintermediate the piston component and the bottom end of the cylinder; apassage being in fluid communication with the upper and lower sectionsof the cylinder, the passage defining a volume; a pressure regulationportion being in communication with the passage and being operative tomodify the volume of the passage for regulating the pressure of a fluiddisposed within the passage and the upper and lower sections of thecylinder; and a damper portion comprising a damper cavity, a separatingpiston component and a biasing component, the separating pistoncomponent being slidably disposed within the damper cavity to definefirst and second sections of the damper cavity, the second section ofthe damper cavity being in fluid communication with the passage, theseparating piston component comprising outer and inner parts, the outerpart being slidably disposed within the damper cavity and beingconfigured to form a seal with an inner surface of the damper cavity,the outer part comprising an interior chamber and a duct, the duct beingin fluid communication with the interior chamber of the outer part andthe second section of the damper cavity, the inner part of theseparating piston component being slidably disposed within the interiorchamber of the outer part of the separating piston component and beingconfigured to form a seal with an inner surface of the interior chamber,the biasing component being disposed in the first section of the damperportion and biasing the inner part of the separating piston componentagainst at least a portion of the damper module.
 17. The steering dampersystem of claim 16, wherein the outer and inner parts of the separatingpiston component each define a bottom surface, the bottom surface of theouter part having a larger surface area than the bottom surface of theinner part.
 18. The steering damper system of claim 17, wherein an axialforce exerted against the inner part in the direction of the secondsection of the damper cavity causes movement of the inner part relativeto the outer part and movement of the outer part relative to the dampercavity.
 19. The steering damper system of claim 18, wherein the axialforce causes the inner part to move in the direction of the secondsection of the damper cavity and the outer part to move in the directionof the first section of the damper cavity.
 20. The steering dampersystem of claim 16, wherein the second section of the damper cavity ofthe damper portion is filled with the fluid.
 21. The steering dampersystem of claim 20, wherein the biasing component biases the inner partto maintain the pressure of the fluid in the damper system.
 22. Thesteering damper system of claim 16, wherein the biasing element is aspring.
 23. The steering damper system of claim 22, wherein the innerpart of the separating piston component defines an actuating area uponwhich the spring can exert an axial force.
 24. The steering dampersystem of claim 16, wherein the inner part of the separating pistoncomponent has a central part that extends upwardly, the central partbeing configured to stabilize the biasing component.
 25. The steeringdamper system of claim 16, wherein the interior cavity of the outer partof the separating piston component defines a stop surface, the stopsurface being configured to contact the bottom surface of the inner partof the separating piston component for limiting the movement of theinner part relative to the outer part of the separating pistoncomponent.
 26. A steering damper system comprising: a piston rodcomprising an elongate shaft, a piston component and a mounting section,the piston component being fixed along the shaft of the piston rod; acylinder being configured with the piston rod slidably disposed thereinand forming a seal between the piston component and an interior surfaceof the cylinder, the cylinder configured with the piston component beinginterposed between upper and lower sections of the cylinder; a passagebeing in fluid communication with the upper and lower sections of thecylinder; and a damper portion comprising: a damper cavity in fluidcommunication with the passage; an outer piston slidably disposed in thedamper cavity and defining a chamber and a duct, the duct being in fluidcommunication with the chamber and the passage; an inner piston slidablydisposed in the chamber of the outer piston; and a biasing componentexerting an axial biasing force against the inner piston; wherein theaxial biasing force biases the inner piston for regulating the pressureof fluid disposed in the system passes intermediate the passage, thedamper cavity, and the chamber of the outer piston.
 27. The steeringdamper system of claim 26, wherein the chamber of the outer pistondefines a stop surface, the stop surface being configured to contact abottom surface of the inner piston for limiting the movement of theinner part relative to the outer piston.
 28. The steering damper systemof claim 26, wherein the inner piston has a central part that extendsupwardly, the central part being configured to stabilize the biasingcomponent.
 29. The steering damper system of claim 26, wherein thepassage defines a volume and the system further comprises a pressureregulation portion in communication with the passage, the pressureregulation portion being operative to modify the volume of the passagefor regulating the pressure of the fluid in the system.